All the major wireless carriers now claim to support "4G" networks. That means broadband data speeds on your smartphone, right? Unfortunately, since "4G" has become a meaningless, catch-all term, it's tough to get a straight answer.

We just completed a survey of all of the major 4G networks in 30 U.S. cities for our annual Fastest Mobile Networks project. And as you'll see from the chart below, "4G" includes a huge range of speeds, just like the idea of "home broadband" does. Before you sign up for cellular data service, you should know what you're getting.

"DSL" 4G vs. "Cable" 4G
You likely have two choices for your home broadband connection: DSL or cable. (If you're lucky, you also have fiber; if you're unlucky, you're stuck with satellite.) These are all considered broadband, but they can be very different speeds.

At the right side of the chart, is the speed for the lowest tier of Verizon's DSL service, at 1.1 to 3Mbps, and the middle tier of Time Warner Cable's Internet service, at around 10Mbps (Time Warner provides an average rather a range). As you can see, the idea of "broadband" has a pretty, well, broad range.

You can pretty much separate each carrier's "4G" into similar "DSL" and "cable" tiers, too. AT&T's HSPA+, MetroPCS's LTE, and Sprint's WiMAX are all down in the DSL zone. And AT&T's and Verizon's LTE networks are up at cable levels. T-Mobile's HSPA+ 42 network straddles both.

Which Carrier Has the Fastest 4G?
If you're just looking for super-fast download speeds, AT&T's new 4G LTE network has the highest peaks. It's very inconsistent, thoughfast in some cities and slow in others, and not available in a lot of the country yet (30 markets at the time of this writing).

Verizon's 4G LTE network delivers the best overall experience. It's available in more cities (258 right now), its speeds are more consistent across the nation, and it has the best upload speeds.

For a budget option, T-Mobile's HSPA+ 42 looks really good. You need to make sure to get an HSPA+ 42 phone to take advantage. Those would be the Samsung Galaxy S Blaze, the HTC One S, the HTC Amaze or the Samsung Galaxy S II right now. If you have any other T-Mobile phone, you won't be getting the full speeds.

Don't Trust Your Carrier
You can't rely on the carriers to be sell 4G honestly. In an appalling example, AT&T spontaneously decided its 3G iPhone 4S was magically "4G" by changing an icon on the screen. One day it was 3G, the next day "4G." Nothing really changed. The phone didn't get any faster. The network didn't get any faster. AT&T just changed the name.

Similarly, both AT&T and T-Mobile have sold phones with "4G" in the name that are slower than most people understand 4G to be, like the HTC Sensation 4G and Motorola Atrix 4G. Sprint now sells "4G LTE" phones with no LTE network connect with, so they operate on 3G across the country.

You can't rely on technology names, either.

We'd love to say that 4G LTE is the gold standard for 4G, but MetroPCS throws a wrench into that plan. As you can see from the chart above, MetroPCS's LTE is much slower than AT&T's or Verizon's, because MetroPCS designed its network to operate very inexpensively rather than speedily. As a result, MetroPCS can charge half what Verizon does for LTE per month.

So What Should You Do?
First, take a look at our main Fastest Mobile Networks feature. If we covered your city, you'll see which network is the best choice. If we don't cover your city, going with Verizon 4G LTE, if it's available in your area, will offer the most consistent 4G experience right now. T-Mobile's HSPA+ is a good backup, if you have solid T-Mobile coverage.

PCMag.com's lead mobile analyst, Sascha Segan, has reviewed hundreds of smartphones, tablets and other gadgets in more than 9 years with PCMag. He's the head of our Fastest Mobile Networks project, one of the hosts of the daily PCMag Live Web show and speaks frequently in mass media on cell-phone-related issues. His commentary has appeared on ABC, the BBC, the CBC, CNBC, CNN, Fox News, and in newspapers from San Antonio, Texas to Edmonton, Alberta.
Segan is also a multiple award-winning travel writer, having contributed...
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